This invention relates to food casings, wrappings, and slurry made primarily from collagen protein.
Smoking of food products such as meats, e.g. sausages and cheeses,is often desirable in order to impart smoke flavor and color into the food product. Unfortunately, such smoking processes have certain disadvantages. In particular, smoke houses require a large amount of pollution control in order to avoid contaminating the environment.
Consequently, liquid smokes have been developed which contain absorbed smoke components which can be incorporated onto or into meat products. This still has disadvantages in that careful control of added liquid smoke is required. Liquid smokes tend to be corrosive and, if not applied properly, cause inconsistent flavor and color. Typically, liquid smoke is applied to the surface of food products either by showering, atomizing or spraying, all being relatively inefficient, i.e., more liquid smoke is lost than is applied. A less common, but not rare, method of utilizing liquid smoke is to blend a measured amount of liquid smoke directly into food products. This method, however, tends to cause artificially harsh smoke flavors and fails to impart a typical smoke color to the surface of the food product.
Collagen sausage casings and films are made by extruding a collagen paste or slurry either in the form of a tube or sheet. The tubes or sheets are subsequently used as a mold to form the sausage by filling the tube, in the case of sausage casings, or wrapping the food product in the collagen film prior to cooking, smoking or drying. A relatively new method of producing sausage products is to simultaneously extrude the sausage mixture and the collagen slurry with the slurry essentially forming the casing on the surface of the sausage mixture. This combination is subsequently treated to cross-link the collagen fibers within the collagen slurry causing the formed casing to have adequate integrity to act as a mold. Liquid smoke is sometimes used as a cross-linking agent. It is important that the collagen not be subjected to the cross-linking agent prior to the co-extrusion process and that the cross-linking agent be added in the proper strength and quantity. Subsequent to co-extrusion and initial cross-linking, these sausages are often drenched with liquid smoke to impart flavor, color and to further cross-link the collagen skin. This drenching process has many of the same disadvantages as those encountered in the traditional methods of sausage production.
Subsequently, the co-extruded sausages are cooked by heating to internal temperatures, generally in the range of 152 to 160 degrees Fahrenheit.
In the area of collagen food wrappings, such as edible collagen sausage casings and collagen slurry, it would, therefore, be desirable to incorporate smoke flavorants and/or colorants directly into the slurry in order to avoid later smoking of contained meat product in a smoke house or by wasteful spraying or drenching with liquid smoke. As previously discussed, this has generally not been possible due to degradation effects of smoke flavorants and colorants upon collagen. In particular, direct exposure of collagen slurry to liquid smoke causes the slurry to cross-link prematurely thus inhibiting formation of the food casing by extrusion into a tube which is to later be stuffed with food product or by direct extrusion onto the surface of a food product.